1. Field of the Invention
The invention is related to a transmission system having at least one transmitter coupled to at least one receiver. The transmitter includes frame assembly means for assembling frames from synchronous data portions and asynchronous data portions, and transmitting means for transmitting the frames to at least one receiver.
The invention is also related to a transmitter, a receiver, a transmitting method and a signal to be used in the above mentioned transmission system.
2. Description of the Related Art
Such a transmission system is known from U.S. Pat. No. 4,914,650.
In the future, communication systems may converge to a single network by which all subscribers are interconnected. Such a network must be suitable for transmission of signals required for various applications, such as telephony, digital TV, and data communication. All these applications require different types of services from the network. Telephony requires a low delay low bit-rate connection. Digital TV transmission requires a substantial higher bit rate but tolerates a larger delay. Data traffic is generally quite bursty and has delay requirements strongly dependent on the type of user application for which it is used.
In order to deal with all these requirements, the transmission system known from the above-mentioned U.S. patent, is arranged for transmitting a signal having fixed positions reserved for synchronous data portions. The remaining space in the signal is available for asynchronous data portions, which are often constituted by a plurality of packets, such as an ATM cells having a 5-byte header and a 48-byte payload area. In the prior art system, an integer number of packets had to be placed between two subsequent synchronous data portion, which can result in some unused space.